Help rebuilding stock k27 turbo (745i)

[Dazza]

When I bought the k27 and related parts from the previous owner, he included an ebay rebuild kit, told me the seals were bad, and that it should be rebuilt.



After taking it apart, it was definitely due for new seals. I doubt it had ever come apart in it's 30+ years on this earth, so getting the turbine shaft our took a bit of persuasion. When it finally did come out, all of the bearings and washer came out too, so I wasn't able to see the exact order they were in. When it came time to put it back together, I tried to follow this exploded view diagram that I found for the Porsche-model k27s that came in 930 cars and other similar-era models:

http://garage.ideola.com/downloads/k26- ... legend.jpg


The problem is that my parts aren't exactly the same as them, and I can't figure out how to make it go back together correctly. The bearings and bearing clips (#1 and #2) go in just fine:


So does the thrust washer:


And the thrust bearing:


And the splash guard:



But after that, it's really tricky. The diagram says I should have some kind of spacer, and it kind of looks like this piece with the broken seal ring:


Followed by this stepped washer that they call a Mating Ring:



But if I install them in that order, it just doesn't look right at all. It also doesn't fit!


However given the shiny areas you can see on the two parts, it does look like they may have fit against each other before disassembly:


Plus the diagram indicates there are 2 more sealing rings (#8) that are supposed to go on the compressor side, but where? I see absolutely nowhere to install any sealing rings, and none came off the turbo when I pulled it apart.

I know that if I try to put it all together the way the diagram indicates, I cannot get the backing plate on at all. But if I swap the order of the spacer and the mating ring, so that the mating ring is on the bottom and sitting inside the splash guard, it actually looks very good. But if I put on the backing plate and tighten the compressor wheel nut, the whole shaft binds and won't spin. I think it's because the spacer with the sealing ring protrudes past the backing plate:



So clearly I'm doing something wrong, but what? Am I missing a part somehow? I've been wrestling with this for several days now and can't figure out what I'm doing wrong. Help!

[Dub-Nub]

I apologize but i have no help for you, i am sure someone will.

I just wanted to say that it would be so fun to solve this puzzle if i had them in front of me. turbochargers are very cool and i wish this was in front of me right now.

Edit:

found this link which shows two different spacers after the thrust washer.

[Dazza]

Yes I found that picture too. It looks like the alternate set of spacers are for a full 360-degree thrust bearing and not for the 270-degree bearing that my turbo uses. Thanks for the tip though!

[Dazza]

Yesterday I spent several hours on the phone with Melett (http://www.melett.com) and Central Motive Power (http://www.centralmotivepower.com). We were trying to figure out what rebuild kit is correct for the BMW-spec k27 and verify that it would come with all the parts needed.

I can't thank the guys at Central Motive Power enough, they were beyond helpful. Their turbo tech Mac Flynn spent an hour on the phone with me cross-referencing parts between KKK, Garrett/Honeywell and even BorgWarner. We found conflicting info from all 3 and it took some real digging to come up with the correct answers, but in the end we succeeded! So without further ado, here's the info you'll need to rebuild a k27!

This is the best exploded-view diagram I could find for the K27. It clearly shows the 2 different versions of the "Flinger ring" assembly (parts 6 & 11), as well as the correct order and orientation for assembly of all components:

Note that the BMW-spec k27 has the "single seal" flinger ring design. You can see the seals listed as part #11 in the diagram above. Many Porsches use the "double seal" flinger ring design. To get the right rebuild parts you need to ID which type of flinger ring your turbo has.


Now to get rebuild parts, you'll need to go through Melett as BorgWarner stopped making parts for these turbos in 2009. Switching to the Melett diagram:
- For the "double seal" design, you'll need Melett part number 1301-027-751
- For the "single seal" design, you need 1301-027-751 plus 1301-027-760



Shop around! Melett only sells through distributors, you cannot order from them directly. When I called a local distributor here in OR they wanted $175 for the rebuild kit!! Central Motive Power in Denver charged me $45 for the exact same kit!

Here's a crude diagram showing how the parts go together on the shaft. The BorgWarner diagram does a good job of showing this as well:


I hope this information is useful to people in the future

[marc79euro645]

Excellent write up Dazza! I have a spare k27 that I may rebuild. Your info and time are appreciated.
good luck
marc